Background

As more biologics are approved, there is increasing interest in comparative effectiveness
research (CER). Health insurance claims databases contain information about outpatient
visits, hospital discharges, procedures, and outpatient pharmacy dispensing but seldom
contain clinical outcomes. In a previous issue of Arthritis Research & Therapy, we presented an algorithm that assessed the clinical effectiveness of rheumatoid
arthritis (RA) biologics which used Veterans Affairs (VA) claims data and which was
validated against the DAS28-ESR (Disease Activity Score 28 using erythrocyte sedimentation
rate) [1]. The algorithm had a sensitivity of 72% (95% confidence interval (CI) = 67% to 77%)
and a specificity of 91% (95% CI = 89% to 93%). In an editorial in the same issue,
Kim and Solomon [2] commented the following: 'a claims-based effectiveness algorithm with acceptable
performance characteristics across different data settings will be a powerful and
desired tool for CER of RA. Such an algorithm will enable large-scale, population-based
studies comparing the effectiveness of different DMARD [disease-modifying antirheumatic
drug] regimens. Such studies will facilitate head-to-head comparisons, supplementing
typical randomized controlled trials and prospective registries that usually include
disease activity. Whether the algorithm will have a similar performance in other claims
databases therefore needs to be further examined'. We performed an independent analysis
to evaluate the algorithm's positive predictive value (PPV) in a commercial claims
data source compared with a clinical gold standard.

Methods

Data came from a previous comparative effectiveness study linking outpatient medical
records from multiple US institutions and physician practices to commercial claims
data from OptumInsight (Eden Prairie, MN, USA) [3] that evaluated the effectiveness of etanercept (ETN), adalimumab (ADA), and infliximab
(INF) in biologic naïve adult RA patients persistent on their initial biologic for
at least 1 year from 2006 to 2008. Two teams of two rheumatologists reviewed each
medical record and categorized clinical change around 1 year as 'much better', 'better',
'no change', 'worse', or 'much worse'. For this study, the biologic was considered
effective if the patient was rated as 'better' or 'much better'. Sensitivity, specificity,
and negative predictive value could not be determined, because patients switching
biologic agents were excluded from the original study. The PPV compared the classification
from the algorithm to the rheumatologist rating. Different compliance thresholds with
the biologic medications used by the algorithm were evaluated as sensitivity analyses.

Result

The majority (76%) of the 429 patients in the study were female, and the mean age
was 51 years. The PPVs were 86.6% in the primary analysis and 86.5% in sensitivity
analyses, similar to that of the original algorithm using VA data. PPV did not differ
significantly by biologic (P >0.2): INF (PPV = 95%), ETN (PPV = 86%), and ADA (PPV = 85%).

Conclusions

This previously published administrative claims-based effectiveness algorithm had
a high PPV across commercial claims data and VA data. This algorithm may be useful
in evaluating the effectiveness of biologic agents by administrative claims data in
future studies.

Abbreviations

Competing interests

The authors declare that they have no competing interests.

Acknowledgements

JRC receives support from the National Institutes of Health (AR053351) and the Agency
for Healthcare Research and Quality (R01HS018517) and reports grants or consulting
work or both with Roche (Basel, Switzerland)/Genentech (South San Francisco, CA, USA),
UCB (Raleigh, NC, USA), Centocor (Horsham, PA, USA), Corrona (Southboro, MA, USA),
Amgen Inc. (Thousand Oaks, CA, USA), Pfizer Inc (New York, NY, USA), BMS (New York,
NY, USA), Crescendo (South San Francisco, CA, USA), and Abbot (Abbott Park, IL, USA).
This research was funded by Immunex Corporation (Seattle, WA, USA), a wholly owned
subsidiary of Amgen Inc., and by Wyeth (Madison, NJ, USA), which was acquired by Pfizer
Inc in October 2009. HY has received research support from Amgen Inc. for unrelated
work. BC and LB are employees of OptumInsight. DJH, DC, and GJJ are employees of Amgen
Inc.